A: Water pumps typically use deep groove ball bearings (6200/6300 series) for radial load, paired with angular contact or four-point contact bearings when thrust is significant. Size by shaft diameter, speed, axial thrust and medium temperature. Standard clean-water pumps often use 6205/6206; high-temp or corrosive duty calls for stainless or hybrid ceramic. Verify L10 life per ISO 281.